Calculate voltages of the following cells at 25^∘ C and under the following conditions. (a) Zn|Z

Calculate voltages of the following cells at 25^∘ C and...

Calculate voltages of the following cells at $25^{\circ} \mathrm{C}$ and under the following conditions. (a) $\mathrm{Zn}\left|\mathrm{Zn}^{2+}(0.50 \mathrm{M}) \| \mathrm{Cd}^{2+}(0.020 \mathrm{M})\right| \mathrm{Cd}$ (b) $\mathrm{Cu}\left|\mathrm{Cu}^{2+}(0.0010 \mathrm{M}) \| \mathrm{H}^{+}(0.010 \mathrm{M})\right| \mathrm{H}_2(1.00 \mathrm{~atm}) \mid \mathrm{Pt}$

Calculate voltages of the following cells at $25^{\circ} \mathrm{C}$ and under the following conditions.
(a) $\mathrm{Zn}\left|\mathrm{Zn}^{2+}(0.50 \mathrm{M}) \| \mathrm{Cd}^{2+}(0.020 \mathrm{M})\right| \mathrm{Cd}$
(b) $\mathrm{Cu}\left|\mathrm{Cu}^{2+}(0.0010 \mathrm{M}) \| \mathrm{H}^{+}(0.010 \mathrm{M})\right| \mathrm{H}_2(1.00 \mathrm{~atm}) \mid \mathrm{Pt}$

Key Concepts

Electrochemical Cell Notation

Electrochemical cell notation is a standardized format used to depict the components and reactions in a galvanic cell. It provides a concise summary that includes the electrodes, the phases of the reactants (solid, aqueous, gas), the direction of electron flow, and, if applicable, the salt bridge separating the two half-cells. This notation is essential for accurately describing and analyzing cell reactions and voltages.

Reaction Quotient

The reaction quotient, Q, is the ratio of the activities or concentrations of the products to the reactants at any point in time during a reaction. In the context of the Nernst equation, Q quantifies how far a reaction is from equilibrium, thereby influencing the electrode potential. It plays a crucial role in determining the cell voltage when conditions differ from the standard state.

Galvanic Cells

Galvanic cells (or voltaic cells) are devices that convert chemical energy into electrical energy through spontaneous redox reactions occurring in two different half-cells. They are the basis for many batteries and are characterized by having an anode (oxidation) and a cathode (reduction) connected by an external circuit and often a salt bridge to maintain ionic balance.

Standard Electrode Potentials

Standard electrode potentials are the intrinsic voltages of half-cells measured under standard conditions (typically 1 M concentration, 1 atm pressure, and 25°C). These potentials provide a reference to determine the direction of redox reactions and the overall cell potential when two half-cells are combined.

Nernst Equation

The Nernst equation is a fundamental relation in electrochemistry that allows for the calculation of the electrode potential under non-standard conditions by accounting for the activities or concentrations of the chemical species involved. It relates the cell potential to the standard electrode potential, temperature, the number of electrons transferred, and the reaction quotient, highlighting how deviations from standard conditions affect the voltage.